This invention generally relates to a dilatation catheter suitable for angioplasty procedures which has a dilatation balloon with heated working surface and particularly to such a catheter which can perfuse blood distally of the balloon during the inflation thereof.
In typical percutaneous transluminal coronary angioplasty (PTCA) procedures, a guiding catheter having a preformed distal tip is percutaneously introduced into the cardiovascular system of a patient through the brachial or femoral arteries and advanced therein until the distal tip thereof is in the ostium of the desired coronary artery. A guidewire and a dilatation catheter having a balloon on the distal end thereof are introduced through the guiding catheter with the guidewire slidably disposed within an inner lumen of the dilatation catheter. The guidewire is first advanced into the patient's coronary vasculature until the distal end thereof crosses the lesion to be dilated and then the dilatation catheter is advanced over the previously introduced guidewire until the dilatation balloon is properly positioned across the lesion. Once in position across the lesion, the flexible, relatively inelastic balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., greater than about 4 atmospheres) to radially compress the atherosclerotic plaque of the lesion against the inside of the artery wall to thereby dilate the lumen of the artery. The balloon is then deflated so that the dilatation catheter can be removed and blood flow resumed through the dilated artery.
Further details of angioplasty procedures and the devices used in such procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,332,254 (Lundquist); U.S. Pat. No. 4,439,185 (Lundquist); U.S. Pat. No. 4,168,224 (Enzmann et al.) U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al.); and U.S. Pat. No. 4,616,652 (Simpson) which are hereby incorporated herein in their entirety.
Steerable dilatation catheters with built-in or fixed guidewires or guiding elements are used with increasing frequency because such catheters generally have smaller deflated profiles than conventional dilatation catheters with movable guidewires or elements with equivalent balloon size. The lower deflated profile of these catheters allows them to cross tighter lesions and to be advanced much deeper into the patient's coronary anatomy. Moreover, the use of steerable low-profile dilatation catheters can shorten the time for the angioplasty procedure because there is no need to first advance a guidewire across a lesion and then slide a conventional dilatation catheter over the previously advanced guidewire to position the balloon thereof across the lesion. Further details of low-profile steerable dilatation catheters may be found in U.S. Pat. No. 4,582,181 (Samson); U.S. Pat. No. 4,619,263 (Frisbie et al.); U.S. Pat. No. 4,641,654 (Samson et al.); and U.S. Pat. No. 4,664,113 (Frisbie et al.) which are hereby incorporated in their entirety by reference thereto.
Recently, efforts have been made to raise the temperature of the stenotic region during the dilation thereof in the belief that such procedures can minimize restenosis and can prevent abrupt reclosure of the artery when the balloon is deflated and removed. See, for example, U.S. Pat. No. 4,799,479 (Spears) and U.S. Pat. No. 4,643,186 (Rosen) Reference is also made to U.S. Pat. No. 4,662,368 (Hussein et al.) and U.S. Pat. No. 4,807,620 (Strul) which disclose catheters with an enlarged heated probe on the distal tip thereof for opening totally occluded arteries.
However, the prior catheters which applied heat to the atheroma had several disadvantages which can limit their usefulness in humans. For example, the direct irradiation employed in some of these devices can cause extensive coagulation of the blood and thermal injury to the tissue which surrounds the catheter at the treatment site. Moreover, frequently the operator's lack of knowledge of the temperature of the heating element can preclude effective moderation of the thermal treatment level. Additionally, non-uniform heating of the treatment area can create uncertainty whether the treatment area is receiving too much or too little heat. Clinically, these disadvantages have in some cases produced extreme pain, vessel reocclusion or aneurysm. None of the prior devices allowed for long-term dilations at elevated temperature.
What has been needed and heretofore unavailable is a balloon dilatation catheter assembly of simple construction and powered by inexpensive equipment which can quickly and uniformly heat up the atheroma during or following the dilatation thereof and preferably which can also perfuse oxygenated blood distally of the catheter when the balloon is inflated to facilitate effective long-term dilations. The present invention satisfies that need.